Safety toggle



Oct. 23, 1956 J. N-ARSTED Wk-2,767,597

SAFETY TOGGLE Filed Oct. 23. 1952 s Sheets-Sheet 1 IN VEN TOR Join Ivar-sized ATTORNEY-5' 2,767,597 Patent ed Oct. 23, 1956 SAFETY TOGGLE John Narsted, Hampstead, Montreal, Quebec, Canada, assignor to Traylor Engineering & Manufacturing Company, Allentown, Pa., a corporation of Delaware Application October 23, 1952, Serial No. 316,413 1 Claim. (Cl. 74-5850 This invention relates to a safety toggle, adapted for use in toggle joints to transmit forces of a predetermined order but to fail when subjected to stress exceeding its design limit, in order to protect associated mechanism from severe damage. The invention relates particularly to a safety toggle adapted for incorporation in a jaw crusher of the type employed to reduce the size of rock, ore and the like.

Jaw crushers having at least one movable jaw are well known, and it is common to drive the movable jaw by means of a pitman and toggle join-t. Occasionally noncrushable objects, such as tramp iron, are introduced into a crusher, and to prevent damage in such case to the frame or jaws of the machine it is known to provide a breakable toggle in the driving mechanism, designed to give way when resistance to the movable jaw reaches a dangerous level. While breakage of a safety toggle necessitates a shutdown and repair or replacement, the time loss and expense are considerably less than severe damage to the crusher would entail.

Safety toggles presently in use include breakable elements designed to fail in shear, that is, disposed across the pressure line of the toggle. These elements, it has been found, subjected constantly to severe vibratory and shear forces, are prone to weaken and fail due merely to progressive shear or similar causes, occ'asioning unnecessary stoppages and replacements. In addition, safety toggles presently in use invariably fall out of their sockets upon failure, so that the toggle must not only be repaired or replaced, but also re-installed.

It is a primary object of the present invention to provide a safety toggle for toggle joints and kindred applications, designed for long life and severe service without unintended failure. A related object is to provide a safety toggle including breakable elements stressed in tension only.

Another object is to provide in a jaw crusher a safety toggle which does not come apart or fall out upon failure of its breakable elements, but remains in place, the members thereof merely pivoting as a hinge until the machine is stopped. Yet another object is to provide a safety toggle for jaw crushers including breakable elements which may be replaced readily and quickly, while the toggle remains installed in customary position in the crusher.

A further object is to provide a safety toggle incorporating breakable elements which may be readily varied in size and number, without disassembly of the toggle or removal from its associated mechanism, whereby the design failure point of the device may be varied at will, with minimum time and trouble. Further objects will be in part evident and in part pointed out hereinafter.

The invention and the novel features thereof may best be made clear from the following description and the accompanying drawings, in which:

Figure 1 is a vertical, t-ransaxial section and partial elevation of a jaw crusher of known type, incorporating in its driving mechanism a preferred embodiment of the present invention;

Figure 2 is an enlarged fragmentary view corresponding to Figure 1, showing details of the safety toggle and its mounting, the toggle being illustrated in failed and hinged position;

Figure 3 is an enlarged vertical sectional view taken on the line 3-3 of Figure 5 Figure 4 is a top plan view of a preferred embodiment of the invention showing a plurality of breakable elements in place therein;

Figure 5 is a side elevational view of the toggle of Figure 4; and

Figure 6 is an enlarged detail view illustrating the preferred manner in which the toggle elements are hingedly connected.

Referring to the drawings, in Figure l is illustrated a.

jaw crusher of known type, comprising the usual rigid; frame v10, fixed jaw 11 and movable jaw 12. The movable jaw 12 is pivotally mounted at its upper end on a shaft 13, carried by the machine frame, and swinging movement is imparted to the lower end thereof by a pitman 1'4 and a toggle joint including toggle 15 and the safety toggle indicated generally as 16.

The pitman 14 is mounted upon the eccentric portion 17 of a transverse shaft, journalled in the machine frame and having a heavy fly wheel 18 thereon. Adjacent its lower end the pitman is provided with oppositely disposed bearing blocks 19, each provided with an outer concave surface 20 adapted to enclose and retain the rounded end of the associated toggle. The opposite end of toggle 15 bears on a block 21 mounted in movable jaw 12, this block also being provided with an outer concave surface 22, and the opposite end of safety toggle 16 bears on surface 23 of block 24, mounted in the adj-ustment member 2'5 which is fixed to the machine frame. The lower end of movable jaw 12 may be connected to a rearwardly extending tension rod 26, extending through an apertu-red lug 27 on the machine frame, with a compression spring 28 interposed between the lug and a washer 29 held on the rod by nuts 30. The tension rod serves to maintain the toggles constantly under compression and assures return movement or retraction of the swinging jaw.

Figures 3, 4 and S disclose a preferred embodiment of the safety toggle, including, as best shown in Figure 3, two opposed members 31, each of which is provided with a rounded outer pressure surface 32 and an inner face surface 33. In Figure 3 the letter A designates a pressure line, which extends between centers of the outer pressure surfaces 32 and indicates the approximate line of force transmission through the toggle, as will be readily understood.

Intermediate the toggle members, and laterally offset somewhat from the pressure line A is disposed a transverse pivot, shown in the form of pin 34. Pin 34 is partially enclosed by the concave cylindrical surfaces 35 formed in the inner sides of the members, and adapted to bear on pin 34 and pivot thereon.

The face surfaces 33 of the toggle members are offset, as shown, from the pressure line A on the same side as and at a greater distance than the pivot pin 34. Provision is made for holding the face surfaces together by breakable means. In the embodiment shown, a plurality of holes or preferably slots 36 are formed in the upper edges of the toggle members, transversely of the members but substantially parallel to the pressure line A. As will hereinafter appear the slots illustrated are most convenient for the insertion of fastening means when such thereto is limited. At the ends of the slots the toggle members are formed into pads 37, whereby the slots are adapted to receive fastening elements such as seals or rivets, or conveniently bolts 38. Conventional lock washers 39 may be provided to maintain the bolts fast against vibrational forces and the like.

The upper faces 40 of the toggle members are desirably machined flat, and may be provided withtapped holes .41. into which eye bolts or similar devices may. be inserted for lifting and handling purposes. To assist in preventing lateral displacement of the assembled meme bers, the opposed face surfaces are recessed to form holes 42, adapted for the reception of dowel pins 43.

To retain the toggle members together when bolts 33 are broken and link them to the pivot pin in hinge relationship, the toggle members may be countersunk at their ends as at 44, illustrated in Figure 6. Inner washers 45 are disposed in countersinks 44 at each end of the pivot pin, these inner washers being welded or otherwise suitably joined to one of the toggle members 31. An outer washer 46 is also provided at each end of the pivot pin, suitably joined as by welding to the other member 31 and also to the pivot pin. In this manner is effected a hinge structure of utmost simplicity, although it will be evident that the toggle members may be hingedly secured to the pivot pin in other suitablemanner.

The operation and function of the invention will now be described in detail. Reciprocating movement of pitman 14, acting through the toggle joint comprising toggle 15 and the safety toggle 16,- causes the movable jaw 12 of the crusher to swing about its pivot shaft 13 toward and away from the fixed jaw 11. In the well known manner,,rnaterial is fed to the upper end of the space between the jaws, and crushed material falls by gravity from the lower end of the jaw space.

In the event a non-crushable object, such as a piece of tramp iron, enters between the jaws, continued operation of the crusher, might result in substantial damage to the machine. To preclude this eventuality, the safety toggle is designed to fail by breakage of the bolts or other fastening elements, on the toggle being subjected to compression stress in excess of a predetermined limit. As will, be evident from a consideration of Figure 3, compression stress through the toggle is transmitted substantially along the pressure line A. The pivot pin 34 being offset laterally from pressure line A, compression stress will tend to cause the toggle members to pivot about the pin, and thereby separate the face surfaces 33. This tendency is constantly resisted by the bolts 38, which are stressed thereby in tension only. It will be evident that the provision of tension elements to absorbthe compression stress obviates all danger of progressive shear failure. Itwill also be evident that the dowel pins 43 serve, while the bolts 33 hold the face surfaces 33 together, to prevent shear load on the bolts due to relative lateral displacement of the members 31. The relative spacing of pivot pin 34 and the bolts 38 from pressure line A determines the leverage action effective on the bolts.

When the design stress of the safety toggle is exceeded, as may be occasioned by the presence of a non-crushable object between the jaws, the bolts 38 will break, whereupon the toggle members may separate but the hinge mechanism comprising washers 45 and 46 functions to retain the toggle members and pivot pin together. A toggle may open to assume a position substantially as shown inFigure 2. If desired, the pivoting movement of the toggle members may be limited by the provision of inclined stop surfaces 47, provided inside the members below the pivot pin, that is, on the opposite side of the pivot pin relative to the face surfaces 33. When the toggle opens, its own weight together with the conformation of its outer pressure surfaces in conjunction with the,

concave block surfaces, combine to maintain the toggle in, position between the pitman and block 24, as will be evident. The toggle may remainopemcrmay oscillate 4 pivotally until, the crusher is brought to a stop, but.can-. not fall out of place.

When the failure has been noted and the crusher brought to a stop, the space between the jaws may be cleared and new bolts inserted into the safety toggle from above while the toggle still remains in position in the mechanism. The bolts are well tightened, or pre-stressed when assembled. It will be evident that the provision of slots 36 atop the toggle members permits most convenient insertion of new bolts thereinto. Since clearing of the jaws and replacement of the breakable tension elements is all that is required, the machine may be repaired and made operable again-in very short order, the stoppage time being reduced to a minimum.

As best shown in Figure 4, a plurality of slots 36 are preferably provided, eight being shown, and a plurality of fastening elements employed. In Figures 4 and 5, six bolts are illustrated. The slots may be made quite large and a large number-provided in order to provide for the crushing of extremely hard materials. In changing the type or character of material worked on, the predetermined stress at which the safety toggle will give way may be altered merely by changing the size or number of bolts employed tohold the face surfaces together. In the embodiment shown, a maximum of eight bolts of diameter corresponding substantially to the width of the slots may be utilized, representing the upper limit of stress at which the toggle will fail. For lower failure points, any lesser number of bolts, or bolts of lesser diameter may be employed as may be desired. Conveniently, the bolts may be provided with a central reduced section 48, to make it possible to determine more accurately the tension stress required -to break them. In designing a toggle ac cording to the invention for a specific application, the range of failure points may spacing of the hinge pin and face surfaces relative to the pressure line.

It will, thus be seen that there has been provided by this invention structure in which the various objects hereinbefore set forth, together with many practical advantages are successfully achieved. Us various possible embodiments may be made of the mechanical features of the above invention, all without departing from the scope thereof, it is to be understood that all matter hereinbefore set forth or shown in the accompanying drawings is to be interpreted as illustrative, and not in a limiting sense.

I claim;

In a crusher of the type having a rigid frame and normally fixed and movable crushing jaws, means for actuating saidv movable crushing jaw including a safety toggle comprising two opposed members, each of said members having an outer pressure surface, an inner face. surface, and an inner inclined stop surface, said face surfaces being laterally offset from the pressure line extending between. said pressure surfaces, said face surfaces being correspondingly recessed to receive dowel pins therebe tweemdowel pinsin said face surface recesses to prevent relative lateral displacement therebetween, a plurality of slots entering the offset portions of said members, said slots being disposed substantially normal to said face surfaces, breakable tension elements in said slots holding said face surfaces together, each of said tension elements including a short portion of reduced section, a pivot disposed transversely intermediate said members between saidface surfaces and said pressure line, and means associated with said pivot for retaining said members to said pivot when said tension elements are broken, said stop surfaces being disposed on the opposite side of said pivot with respect to said face surfaces whereby said stop surfaces are adapted to limit pivotal movement of the members about the pivot (References on followingpage) also be varied by varying the References Cited in the file of this patent UNITED STATES PATENTS Egbert May 15, 1928 Georg Aprg2l, 1931 Rasmussen Dec. 29, 1936 Earhart May 11, 1948 Rutledge June 21, 1949 

